The present invention relates to a heat exchanger for solar energy generators, and in particular to a heat exchanger which can be employed in the collectors receiving the solar rays from the reflectors of these generators.

The known heat exchangers for solar energy generators generally comprise one or more ducts which are arranged with the longitudinal axis substantially perpendicular with respect to the solar rays and which are crossed by a fluid to be heated with the energy transmitted by these rays. The efficiency of the heat exchange between the outer surface of the ducts and the fluid flowing therein depends on many factors, among which the shape, the material and the size of the same ducts.

It is therefore an object of the present invention to improve the efficiency of the known heat exchangers. Said object is achieved with a heat exchanger, the main features of which are disclosed in the first claim and other features are disclosed in the subsequent claims.

Thanks to the particular fins which is provided with, the heat exchanger according to the present invention has a high efficiency in absorbing the solar energy. As a matter of fact, the arrangement and the "funnel" shape of said fins allows to absorb in an optimal manner not only the energy directly transmitted by the solar rays hitting the fins, but also the energy, even if very low, reflected by these fins.

Further advantages and features of the heat exchanger according to the present invention will become clear to those skilled in the art from the following detailed and non-limiting description of an embodiment thereof with reference to the attached drawings, wherein: — figure 1 shows a partial perspective view of the heat exchanger;

- figure 2 shows a partial and enlarged side view of the heat exchanger of figure 1; and

— figure 3 shows a partial perspective view of the heat exchanger of figure 1 in its case.

Referring to figures 1 and 2, it is seen that the heat exchanger according to the present invention comprises in a known way one or more ducts 1 suitable for being exposed to a source of solar rays 2, for example the reflector of a solar energy generator, and for containing a fluid to be heated with the energy transmitted by these rays. Ducts

1 are preferably arranged parallel on a plane and are mutually connected by connections

3 fixed to their ends, so as to form one or more serpentines.

According to the invention, a plurality of fins 4, for example rectangular, are arranged transversely with respect to ducts 1, in particular are provided with holes for being crossed by the latter. At least one of edges 4a, 4b turned toward the solar rays 2 of two adjacent fins 4 is inclined so that these edges 4a, 4b converge with an angle a less than 90°, and so on for the other fins 4, so as to form a series of pairs of fins 4 with edges 4a, 4b converging two by two. Preferably, the distance between the ends of the contiguous edges 4a, 4b of two converging fins 4 is substantially null. At least one of edges 4c, 4d of two adjacent fins 4, which are opposite with respect to the converging edges 4a, 4b of the same fins 4, is inclined so that these edges 4c, 4d diverge with an angle b less than 90°, and so on for the other fins 4, so as to form a series of pairs of fins

4 with edges 4c, 4d diverging two by two where edges 4a, 4b of the same fins 4 converge. Fins 4 form thus an at least partially triangular wave which develops along the longitudinal axis of ducts 1. Angles a and/or b between the converging edges 4a, 4b or the diverging edges 4c, 4d of fins 4 are preferably comprised between 25° and 45°. In particular, angles a and b are substantially the same. Fins 4 and/or ducts 1 are coated with dark and opaque paints for improving the solar energy absorption.

Figure 3 shows fins 4 enclosed in an inner case 5 open only from the side turned toward the solar rays 2. This inner case 5 is coated by a layer of an insulating material 6, in turn covered by an outer case 7. The ends of ducts 1 and connectors 3 are housed in a container 8 provided with holes for mounting and connecting the heat exchanger to the solar energy generator.

Possible variations and/or additions may be made by those skilled in the art to the hereinabove described and illustrated embodiment of the invention while remaining within the scope of the same invention.